/*********************************************************************
 * Copyright (C) 2007 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.biff.formula;

import jxl.biff.IntegerHelper;

import java.util.Stack;

/**
 * Base class for those tokens which encapsulate a subexpression
 */
abstract class SubExpression extends Operand implements ParsedThing {
    /**
     * The number of bytes in the subexpression
     */
    private int length;

    /**
     * The sub expression
     */
    private ParseItem[] subExpression;

    /**
     * Constructor
     */
    protected SubExpression() {
    }

    /**
     * Reads the ptg data from the array starting at the specified position
     *
     * @param data the RPN array
     * @param pos the current position in the array, excluding the ptg identifier
     * @return the number of bytes read
     */
    public int read(byte[] data, int pos) {
        length = IntegerHelper.getInt(data[pos], data[pos + 1]);
        return 2;
    }

    /**
     * Gets the operands for this operator from the stack
     */
    public void getOperands(Stack s) {
    }

    /**
     * Gets the token representation of this item in RPN.  The Attribute
     * token is a special case, which overrides anything useful we could do
     * in the base class
     *
     * @return the bytes applicable to this formula
     */
    byte[] getBytes() {
        return null;
    }


    /**
     * Gets the precedence for this operator.  Operator precedents run from
     * 1 to 5, one being the highest, 5 being the lowest
     *
     * @return the operator precedence
     */
    int getPrecedence() {
        return 5;
    }

    /**
     * Accessor for the length
     *
     * @return the length of the subexpression
     */
    public int getLength() {
        return length;
    }

    protected final void setLength(int l) {
        length = l;
    }

    public void setSubExpression(ParseItem[] pi) {
        subExpression = pi;
    }

    protected ParseItem[] getSubExpression() {
        return subExpression;
    }
}
